Spindle comprising a data storage element

ABSTRACT

The invention relates to a spindle ( 9 ) for a machine tool, having a housing ( 12 ) to accommodate an electric motor ( 11 ) and a shaft ( 13 ) driven by the latter and having a tool holder for a tool ( 10 ) for machining workpieces, at least one data acquisition element ( 2 ) being provided to record operating and/or state data of the spindle ( 9 ), and at least one spindle-integrated data storage element ( 1 ) being provided to store the recorded data from the data acquisition element ( 2 ).

[0001] The invention relates to a spindle for a machine tool having thefeatures of the preamble of patent claim 1. Furthermore, the inventionrelates to a method of operating a spindle for a machine tool having thefeatures of the preamble of patent claim 23.

[0002] Spindles for machine tools are known as the prior art, thespindle being connected to a machine control system of the machine toolin order to drive the electric motor and in order to acquire the datafrom the data acquisition elements (sensors) of the spindle. Separateacquisition or processing of the data from the sensors, for example bythe manufacturer of the spindle, is not possible without intervention inthe machine control system of the machine tool.

[0003] The invention is based on the object of providing a spindle for amachine tool and a method of operating a spindle for a machine tool, inwhich separate acquisition of the operating and/or state data of thespindle is made possible without intervention in the machine controlsystem of the machine tool.

[0004] The object is achieved for the spindle by the features of thedefining part of patent claim 1 in conjunction with the features of thepreamble. Advantageous embodiments of the spindle are described in thefurther patent claims 2-22. With regard to the method, the object isachieved by the features of the defining part of patent claim 23 inconjunction with the features of the preamble. Advantageous methodvariants are described in the further patent claims 24-31.

[0005] In the following text, the term “spindle” is to be understood ingeneral terms and comprises, for example, a motor spindle having ahousing to accommodate an electric motor and a belt-driven spindle withan external drive motor. Furthermore, the spindle can be used either tohold tools (for example for grinding machines) or to hold workpieces(for example for turning machines).

[0006] In the spindle according to the invention, at least onespindle-integrated data storage element is provided to store therecorded data from the data acquisition element or elements (sensors) ofthe spindle. In this case, the term “spindle-integrated” is to beunderstood to mean both integration of the data storage element in thehousing of the spindle and fitting to the outside of the housing of thespindle.

[0007] As distinct from the prior art, the data storage element is notassociated with the motor control system of the machine tool orintegrated physically into the motor control system. In the event ofreplacement of the spindle, the data storage element can be readseparately by the service personnel, that is to say by the manufacturerof the spindle, and suitable diagnostic systems can be connected to thedata storage element without intervention in the machine control systemof the machine tool being necessary. Therefore—if desired—access by themachine control system (and therefore by the manufacturer or operator ofthe machine tool) to the data storage element can also be blocked,partially or completely, in order to make internal and secret data whichis related to the spindle accessible only to the manufacturer of thespindle. This may be of importance, for example, in connection withfunctional disruption and any guarantee claims associated with this bythe manufacturer or operator of the machine tool with respect to themanufacturer of the spindle.

[0008] A plurality of sensors are advantageously provided in thespindle, for example for determining the temperature of the bearings andof the motor, the angular position, the vibration travel, the leakageetc., which store the recorded operating and state data in thespindle-integrated data storage element. When the spindle is running, inthe event of repair or in the event of replacement of the spindle, byreading the spindle-integrated data storage element, conclusions aboutthe operating behavior of the spindle can be drawn, and the causes offunctional disruption can be determined or investigated.

[0009] In a further advantageous embodiment, the spindle has at leastone spindle-integrated data processing element connected to the datastorage element for processing or conditioning the data stored in thedata storage element and coming from the sensors of the spindle. Thespindle can therefore have an integrated EDP unit, in which the sensordata can be digitized and conditioned. In this case, individual measuredvariables from various sensors can also be processed in combined form sothat, for example if temperature data is linked to rotational speeddata, a corresponding axial displacement of the spindle shaft of thespindle can be determined with micron accuracy. In addition, the sensordata can be conditioned to produce a data bus structure.

[0010] In a particularly advantageous embodiment, the data processingelement is used for the data compression of the data recorded by thedata acquisition element, in particular of recorded vibration signals.This data compression can be achieved by an encoder integrated in thedata processing element, as a result of which the amount of datarecorded by the data acquisition element is reduced, by unimportantcomponents of this quantity of data being ignored. This produces datapackets of reduced size, which can be passed on via thespindle-integrated interface to data transmission, for example to anexternal EDP station, it being possible there for a frequency analysisof the recorded vibration signals to take place. As a result of the datacompression in the data processing element, the recorded vibrationsignals can be transmitted from the data processing element to theexternal EDP station within a tolerable short time period.

[0011] The data storage element and/or the data processing element ofthe spindle can be connected to the machine control system of themachine tool in order to forward individual items or a specific amountof desired sensor data to the machine control system. Here, forwardingspecific sensor data which is intended only for the manufacturer of thespindle can be prevented.

[0012] According to a further advantageous embodiment, a data storageelement and/or the data processing element of the spindle has/have aspindle-integrated interface, in order to permit data transmission, inparticular to an external EDP station.

[0013] In this connection, provision is made in particular of aspindle-integrated modem element, for example in the manner of a plug-incard for personal computers, in order to be able to dial into therespective spindle via a provider from an external EDP station (forexample a personal computer at the manufacturer of the spindle) and inorder to make data transmission possible between the external EDPstation and the unit comprising data storage element and/or dataprocessing element and modem element.

[0014] In this case, data transmission between spindle and the externalEDP station via the spindle-integrated interface can take place inaccordance with an Internet data protocol. The connection betweenexternal EDP station and spindle can be provided as required via atelephone line or else be present as a dedicated line. Furthermore, allthe line systems (for example including the power network) can be usedfor data transmission.

[0015] According to an advantageous embodiment, a data connection fromthe spindle to an external EDP station can also be produced as required,so that, starting from the spindle, by dialing the IP address of theexternal EDP station, a data connection like that between two personalcomputers is produced.

[0016] In the event of data transmission in accordance with an Internetdata protocol, in addition or as an alternative, a TCP/IP data protocol(Transmission Control Protocol/Internet Protocol), an SMTP data protocol(Simple Mail Transfer Protocol), a POP data protocol (Post OfficeProtocol), HTTP data protocol (Hypertext Transfer Protocol), NNTP dataprotocol (Network News Transfer Protocol), an FTP data protocol (FileTransfer Protocol) and/or a WAP data protocol (Wireless ApplicationProtocol) can be used.

[0017] The selection of the respective data protocol depends inter aliaon the type and amount of data to be transmitted. If it is desired thatthe service personnel want to interrogate specific characteristic valuesof the spindle from the data storage element via a mobile telephone, forexample a data transmission in accordance with the WAP data protocol(Wireless Application Protocol) could take place.

[0018] The spindle-integrated interface can be designed for cable-boundor cable-free data transmission (for example via radio signals, infraredsignals, etc.). In the case of cable-free data transmission, the sensordata stored in the spindle-integrated data acquisition element can beread out, for example by service personnel, via a suitableradio-controlled or infrared-controlled data reader.

[0019] The spindle-integrated interface can be designed, for example, asan RS232/RS485 interface, by which means, for example, an external EDPstation, which is used as a diagnostic computer by the service personnelon site, can be connected to the spindle-integrated data storage elementand/or data acquisition element in order to read out the sensor datapresent.

[0020] Furthermore, the interface can be designed as a data businterface, for example for the transmission of data bus protocols inaccordance with the Standards USB (PC), PROFIBUS-DP, INTERBUS-S, CAN-BUSand SERCOS.

[0021] In this case, the spindle-integrated interface can be connected,for example, to the external EDP station or else—if desired—to themachine control system of the machine tool, in order to permit (limited)access by the machine control system to the spindle-integrated datastorage element and/or data acquisition element. The spindle-integratedinterface can have a testing function and be used both for datatransmission in each case of different data streams to the machinecontrol system of the machine tool and, for example, to the external EDPstation.

[0022] Alternatively, two spindle-integrated interfaces can also beprovided, one as a connection to the machine control system and theother as a connection to the external EDP station.

[0023] Overall, the term “external EDP station” designates any technicalelement which is suitable to receive and/or transmit data for thepurpose of data transmission. This can be, for example, a local EDPdiagnostic system belonging to the service personnel, a mobile telephoneor a personal computer connected to the spindle via remote datatransmission (for example via an Internet connection) or an EDP systembelonging to the manufacturer of the spindle.

[0024] In the method according to the invention of operating a spindlefor a machine tool, the recorded data from a data acquisition element(sensor) of the spindle is stored by at least one spindle-integrateddata storage element. In addition, a spindle-integrated data processingelement may be provided, by which the sensor data stored in the datamemory is processed.

[0025] Data transmission and communication between the spindle and, inparticular, an external EDP station is made possible via an interface ofthe spindle via which, either starting from the spindle or starting fromthe external EDP station, a data connection can be built up andmaintained.

[0026] According to a particularly advantageous method variant, datacompression of the vibration signals recorded by the data acquisitionelement is carried out in the data processing element, the scope of thedata being reduced considerably and it being possible for rapidtransmission of the remaining quantity of data to take place via thespindle-integrated data interface, for example to an external EDPstation for frequency analysis or monitoring. In this case, the datacompression method can have recourse to methods which are already knownfor the data compression of audio signals (for example compressionmethods in accordance with the “MPEG 1 Part 3” Standard).

[0027] In a modification of a compression method in accordance with the“MPEG 1 Part 3” Standard, the psycho-acoustic model used there for datacompression, which is oriented to the subjective audiological impressionof the user, is advantageously replaced by another compression model,for example by a machine-acoustic model, a model for the generation ofvibrations or a model of the machine dynamics.

[0028] Thus, characteristic frequencies of the bearing elements (forexample of ball bearings) of the spindle shaft mounting of the spindlecan be acquired, compressed and transmitted onward. In connection withthe frequency monitoring of ball bearings, for example cage circulationfrequencies, inner/outer ring rollover frequencies and side bands causedby modulation of these vibrations, etc. occur. Characteristicfrequencies of ball bearings are predefined structurally by the designconstruction of the ball bearing and can be used for a compression modelin an encoder integrated in the data processing element.

[0029] In this way, the vibration information recorded by the dataacquisition elements can be reduced considerably, which means thatfaster data transmission can take place via a data interface of thespindle to an external EDP station, in which decompression of thetransmitted data by a decoder can take place.

[0030] In a specific example, during operation of the spindle accordingto the invention at a spindle shaft rotational speed of about 60 000rev/min., an interfering frequency of about 8 kHz of the drive motor ofthe spindle can occur. At the same time, cage revolution frequencies,which are to be recorded and monitored, of the bearing elements of thespindle shaft of the order of magnitude of about 0.4 kHz can occur. In amachine-acoustic compression model, the undesired interfering frequencyof 8 kHz can then be suppressed and not taken into account in the datacompression in the encoder of the data processing element.

[0031] In general, any desired various and refined compression modelsare conceivable and can be adapted to the respective spindleconstruction and the respective operating conditions.

[0032] The invention is explained in more detail in the drawing FIGUREusing an exemplary embodiment.

[0033] The drawing FIGURE shows, in a schematic sectional illustration,a spindle 9 having a housing 12, in which an electric motor 11 isaccommodated, which drives a shaft 13 accommodated in the bearings 14,15 and having a tool 10.

[0034] According to the drawing FIGURE, the heat produced duringoperation in the region of the electric motor 11 and of the bearings 14,15 is led away by the cooling means 16, 17.

[0035] Furthermore, a hydraulic unit 18 is provided, which can beactivated in order to change the tool 10.

[0036] The machine control system 4 of the machine tool, which is notspecifically depicted, in which the spindle 9 is accommodated is used todrive, for example, a tool changing element 19, a lubricating device 20,a rectifier 21 and a cooling unit 22 which each—as depicted—areconnected inter alia to the hydraulic unit 18, the electric motor 11 andthe cooling means 16, 17.

[0037] Finally, the spindle 9 also has data acquisition elements(sensors) 2, for example temperature, vibration, angular or rotationalspeed sensors, etc.

[0038] Such data acquisition elements 2, such as the data acquisitionelement 2 b (rotational speed sensor), are connected directly to themachine control system 4, for example the inverter 21, to store thesensor data in the case of spindles according to the prior art (notdepicted).

[0039] According to the invention, the data acquisition elements 2,depicted here by way of example as a temperature sensor 2 a androtational speed sensor 2 b, are also or only connected to thespindle-integrated data storage element 1.

[0040] In the data storage element 1, the sensor data from the dataacquisition elements 2 a, 2 b and further data acquisition elements notdepicted is stored and, if desired, is conditioned or combined in thelikewise spindle-integrated data processing element 3.

[0041] Finally, the data storage element 1 and the data acquisitionelements 2 can be read out via the interface 5, if desired, by using alikewise spindle-integrated modem element 7.

[0042] Via the interface 5, a data connection 24 can be produced to anexternal EDP station 6 or a telephone connection 8.

[0043] Data interchange between EDP station 6 and data storage element 1and/or data acquisition element 2 can, as described, be carried out inaccordance with the various (Internet) data protocols and can take placein a cable-free manner (for example via radio or infrared etc.) or in acable-bound manner.

[0044] Here, the EDP station 6 can be located in the immediatesurroundings of the spindle 9 and used by the service personnel, forexample as a diagnostic computer. Furthermore, the EDP station 6 as apersonal computer or as an EDP system, for example belonging to themanufacturer of the spindle 9, can communicate with the data storageelement 1 or the data acquisition element 2 by means of the remote datatransmission via the data connection 24 (for example via an Internetconnection).

[0045] According to the invention therefore, the recorded data from thedata acquisition elements 2, that is to say the spindle-integratedsensors, can be recorded separately and read out separately, withoutthere having to be any intervention in the machine control system 4 andtherefore agreement of the manufacturer or of the operator of themachine tool.

[0046] The interface 5 can also be connected via the connection 25 tothe motor control system 4, it being possible via appropriate coding orother identification for the data from the data storage element 1 andfrom the data acquisition element 2 to be determined, said sensor databeing passed on from the data acquisition elements 2 to the machinecontrol system 4 or to the EDP station 6.

[0047] Overall, the spindle 9 according to the invention makes itpossible to accommodate spindle-internal recorded sensor data from thedata acquisition elements 2 optionally internally in the spindle in thedata storage element 1 (for example for further processing in the dataprocessing unit 3) or to pass said data on to the machine control system4.

1. A spindle for a machine tool, in particular a motor spindle having ahousing to accommodate an electric motor and a shaft driven by thelatter, in particular having a tool holder for a tool for machiningworkpieces, at least one data acquisition element being provided torecord operating and/or state data of the spindle, wherein at least onespindle-integrated data storage element (1) is provided to store therecorded data from the data acquisition element (2).
 2. The spindle asclaimed in claim 1, wherein at least one spindle-integrated dataprocessing element (3) connected to the data storage element (1) isprovided.
 3. The spindle as claimed in claim 2, wherein the dataprocessing element (3) is provided for the data compression of recordeddata from the data acquisition element (2).
 4. The spindle as claimed inone of claims 1-3, wherein the data storage element (1) and/or the dataprocessing element (3) is/are connected to a machine control system (4)of the machine tool for the purpose of data transmission.
 5. The spindleas claimed in one of claims 1-4, wherein the data storage element (1)and/or the data processing element (3) has/have at least onespindle-integrated interface (5) for data transmission, in particular toan external EDP station (6).
 6. The spindle as claimed in one of claims1-5, wherein a spindle-integrated modem element (7) is provided toproduce a data connection, in particular to a telephone connection (8).7. The spindle as claimed in either of claims 5 and 6, wherein theinterface (5) is provided for data transmission in accordance with anInternet data protocol.
 8. The spindle as claimed in claim 7, whereinthe interface (5) is used for data transmission in accordance with theTCP/IP data protocol.
 9. The spindle as claimed in claim 7 or 8, whereinthe interface (5) is used for data transmission in accordance with theSMTP data protocol.
 10. The spindle as claimed in one of claims 7-9,wherein the interface (5) is used for data transmission in accordancewith the POP data protocol.
 11. The spindle as claimed in one of claims7-10, wherein the interface (5) is used for data transmission inaccordance with the HTTP data protocol.
 12. The spindle as claimed inone of claims 7-11, wherein the interface (5) is used for datatransmission in accordance with the NNTP data protocol.
 13. The spindleas claimed in one of claims 7-12, wherein the interface (5) is used fordata transmission in accordance with the FTP data protocol.
 14. Thespindle as claimed in one of claims 7-13, wherein the interface (5) isused for data transmission in accordance with the WAP data protocol. 15.The spindle as claimed in one of claims 7-14, wherein the data storageelement (1) and/or the data processing element (3) has an allocated IPaddress.
 16. The spindle as claimed in one of claims 5-15, wherein theinterface (5) is designed for cable-free data transmission (for examplevia radio signals, infrared signals etc.).
 17. The spindle as claimed inone of claims 5-16, wherein the interface (5) is designed as anRS232/RS485 interface.
 18. The spindle as claimed in one of claims 5-17,wherein the interface (5) is designed as a data bus interface for datatransmission in accordance with the USB (PC) protocol.
 19. The spindleas claimed in one of claims 5-18, wherein the interface (5) is designedas a data bus interface for data transmission in accordance with thePROFIBUS-DP protocol.
 20. The spindle as claimed in one of claims 5-19,wherein the interface (5) is designed as a data bus interface for datatransmission in accordance with the INTERBUS-S protocol.
 21. The spindleas claimed in one of claims 5-20, wherein the interface (5) is designedas a data bus interface for data transmission in accordance with theCAN-BUS protocol.
 22. The spindle as claimed in one of claims 5-21,wherein the interface (5) is designed as a data bus interface for datatransmission in accordance with the SERCOS protocol.
 23. A method ofoperating a spindle, in particular a machine spindle for a machine tool,having a housing to accommodate an electric motor and a shaft driven bythe latter, in particular having a tool holder for a tool for machiningworkpieces, at least one data acquisition element being provided torecord operating and/or state data of the spindle, in particular amethod of operating a spindle as claimed in one of claims 1-22, whereinthe recorded data from the data acquisition element is stored by atleast one spindle-integrated data storage element.
 24. The method asclaimed in claim 23, wherein the data stored in the data memory isprocessed in a spindle-integrated data processing element.
 25. Themethod as claimed in either of claims 23 and 24, wherein datatransmission to an external EDP station is carried out via an interfaceof the data storage element and/or data processing element.
 26. Themethod as claimed in one of claims 23-25, wherein self-diagnosis of thespindle is carried out via the data storage element and/or the dataprocessing element.
 27. The method as claimed in either of claims 25 and26, wherein data signals are transmitted from the spindle to theexternal EDP station via the interface, for example in the event of afunctional disruption.
 28. The method as claimed in one of claims 25-27,wherein state and/or operating data of the spindle are interrogated bythe external EDP station by means of data transmission.
 29. The methodas claimed in one of claims 24-28, wherein data compression of the datarecorded by the data acquisition element is carried out in the dataprocessing element.
 30. The method as claimed in claim 29, wherein thedata compression is carried out by data compression methods which aresuitable in particular for the data compression of recorded vibrationsignals.
 31. The method as claimed in claim 30, wherein data compressionis carried out by a data compression method according to the “MPEG 1Part 3” Standard or a comparable compression method.